Optical recording medium

Abstract

A heat mode recordable, optical recording medium comprising: a transparent substrate; a recording layer containing a dye; and a reflective layer, wherein the recording layer comprises an organic dye, and the medium has an optimum recording power of at least 25 mW when recorded at a linear velocity v (m/sec) with a laser beam having a wavelength of 600 to 700 nm, the optimum recording power being defined as a recording power (Po) at which a jitter in recording 8/16 modulation signals is lowest and being represented by equation: Po=P 1×{square root}{square root over (( v /3.5))}˜1.5 P 1×{square root}{square root over (( v /3.5))} in which P1 is an optimum recording power in recording at a linear velocity of 3.5 (m/sec).

1 . A heat mode recordable, optical recording medium comprising: 
 a transparent substrate;    a recording layer containing a dye; and    a reflective layer,    wherein the recording layer comprises an organic dye, and    the medium has an optimum recording power of at least 25 mW when recorded at a linear velocity v (m/sec) with a laser beam having a wavelength of 600 to 700 nm, the optimum recording power being defined as a recording power (Po) at which a jitter in recording 8/16 modulation signals is lowest and being represented by equation:        Po=P 1×{square root}{square root over (( v /3.5))}˜1.5 P 1×{square root}{square root over (( v /3.5))}   in which P1 is an optimum recording power in recording at a linear velocity of 3.5 (m/sec).    
     
     
         2 . The optical recording medium according to  claim 1 , wherein the organic dye is an oxonol dye.  
     
     
         3 . The optical recording medium according to  claim 2 , wherein the oxonol dye is represented by formula (I):  
       
         
           
           
               
               
           
         
       
       wherein Za 1  and Za 2  each independently represents an atomic group necessary to form an acidic nucleus; Ma 1 , Ma 2  and Ma 3  each independently represents a substituted or unsubstituted methine group; ka represents an integer of 0 to 3; when ka is 2 or 3, Ma 1 's and Ma 2 's may be same or different, respectively; Q represents an ion neutralizing charge; and y represents a number necessary for neutralization.  
     
     
         4 . The optical recording medium according to  claim 3 , wherein the ion represented by Q is represented by formula (II)  
       
         
           
           
               
               
           
         
       
       wherein R 11 , R 12 , R 14 , R 15 , R 16 , R 17 , R 19 , and R 20  each independently represents a hydrogen atom or a substituent; and R 13  and R 18  each independently represents a substituent.  
     
     
         5 . The optical recording medium according to  claim 1 , which has a structure selected from: 
 (1) a structure in which a first laminate comprising a transparent disk substrate with a diameter of from 117 to 123 mm or from 77 to 83 mm and a thickness of from 0.5 to 0.7 mm having a pregroove formed thereon at a track pitch of from 0.6 to 0.9 μm and a recording layer containing a dye formed on a pregrooved side of the substrate is joined with a second laminate having same dimension and structure as the first laminate with the recording layer of the first laminate and the recording layer of the second laminate facing inside to have a total thickness of from 1.0 to 1.4 mm; and    (2) a structure in which the first laminate is joined with a protective disk substrate with the recording layer facing the protective disk substrate to have a total thickness of from 1.0 to 1.4 mm.    
     
     
         6 . An optical recording method comprising recording an optical recording medium comprising a transparent substrate, a recording layer containing an organic dye and a reflective layer with a laser beam having a wavelength of 600 to 700 nm at a linear velocity v (m/sec) with an optimum recording power of at least 25 mW, the optimum recording power being defined to be a recording power (Po) at which a jitter in recording 8/16 modulation signals is lowest and represented by equation:  
           Po=P 1×{square root}{square root over (( v /3.5))}˜1.5 P 1×{square root}{square root over (( v /3.5))} 
       where P1 is an optimum recording power in recording at a linear velocity of 3.5 (m/sec).  
     
     
         7 . An optical recording medium used in the optical recording method according to  claim 6 .  
     
     
         8 . The optical recording medium according to  claim 7 , wherein the organic dye is an oxonol dye.  
     
     
         9 . The optical recording medium according to  claim 8 , wherein the oxonol dye is represented by formula (I):  
       
         
           
           
               
               
           
         
       
       wherein Za 1  and Za 2  each independently represents an atomic group necessary to form an acidic nucleus; Ma 1 , Ma 2 , and Ma 3  each independently represents a substituted or unsubstituted methine group; ka represents an integer of 0 to 3; when ka is 2 or 3, Ma 1 's and Ma 2 's may be same or different, respectively; Q represents an ion neutralizing charge; and y represents a number necessary for neutralization.  
     
     
         10 . The optical recording medium according to  claim 9 , wherein the ion represented by Q is represented by formula (II)  
       
         
           
           
               
               
           
         
       
       wherein R 11 , R 12 , R 14 , R 15 , R 16 , R 17 , R 19 , and R 20  each independently represents a hydrogen atom or a substituent; and R 13  and R 18  each independently represents a substituent.  
     
     
         11 . The optical recording medium according to  claim 7 , which has a structure selected from: 
 (1) a structure in which a first laminate comprising a transparent disk substrate with a diameter of from 117 to 123 mm or from 77 to 83 mm and a thickness of from 0.5 to 0.7 mm having a pregroove formed thereon at a track pitch of from 0.6 to 0.9 μm and a recording layer containing a dye formed on a pregrooved side of the substrate is joined with a second laminate having same dimension and structure as the first laminate with the recording layer of the first laminate and the recording layer of the second laminate facing inside to have a total thickness of from 1.0 to 1.4 mm; and    (2) a structure in which the first laminate is joined with a protective disk substrate with the recording layer facing the protective disk substrate to have a total thickness of from 1.0 to 1.4 mm.